If you want to manage the photos in your device, 3uTools allows you to delete plenty of photos in your device conveniently.
However, when you fail to delete photos, you can operate as the following to fix it.
Operations
1. Please make sure you switch off iCloud Photo Library
2. If you take the photos or import them after you connect your device to 3uTools, plesae click “Refresh”, then try to delete photos again. If this trick does not work, please re-connect your device to PC.
3. If you does not turn on screen, please turn it on then re-connect to 3uTools.
4. Please re-plug the device and check the USB cable and port to confirm the connection.
5. If all the above tips are effectless, you can find the device folder in Computer → Portable Devices, then you can delete the photo from here.